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Titanium dioxide (TiO2) nanoparticles have been extensively used to modify the optical properties of various types of materials. In particular, they have been intensively loaded onto polymer fibers to quench the light reflection. In situ polymerization and online addition are two common strategies for fabricating TiO2-loaded polymer nanocomposite fibers. The former does not require separate preparation of masterbatches as the latter does and therefore has its advantages in terms of decreasing the fabrication steps and economic costs. Moreover, it has been found that in situ-polymerized TiO2-loaded polymer nanocomposite fibers (e.g., TiO2/poly(ethylene terephthalate) fibers) usually have enhanced light-extinction properties over those prepared by the online addition process. Intuitively, there should be a difference in the filler particle dispersion for the two fabrication processes. This hypothesis has not yet been tackled due to the technical difficulty in acquiring the three-dimensional (3D) filler morphology inside the fiber matrix. In this paper, we report a study using the powerful focused ion beam-scanning electron microscopy (FIB-SEM) with a resolution of 20 nm to directly acquire the 3D microstructure of TiO2/poly(ethylene terephthalate) nanocomposite (TiO2/PET) fibers. This microscopy technique allows us to characterize the particle size statistics and the dispersion inside TiO2/PET fibers. We have found that the particle size of TiO2inside the fiber matrix can be well modeled by Weibull statistics. Surprisingly, we find that TiO2nanoparticles form more significant agglomeration in the in situ-polymerized TiO2/PET fibers. This observation is contrary to our common understanding of the two fabrication processes. Namely, slightly altering the particle dispersion with increased TiO2filler size helps improve the light-extinction properties. The slightly increased filler size may have altered the Mie scattering between the nanoparticles and the incident visible light, leading to enhanced light-extinction properties of in situ-polymerized TiO2/PET nanocomposite fibers.

Graphical Abstract:

The local coordination structure of metal atoms in single-atom catalysts (SACs) greatly influences their catalytic performance. And for most SACs, single metal atoms were anchored on carbon materials with N or C coordination. However, the rational design of oxygen-containing SACs and analyzing its structure–performance relationship remain challenging. Herein, we used amino-rich compounds to tailor the metatungstate and fix the W atoms and finally obtained the oxygen-containing W-SACs. The structural evolution of tungsten and its coordination atoms were tracked by electrospray ionization high-definition mass spectrometry. Furthermore, aberration-corrected transmission electron microscopy, X-ray absorption fine-structure spectroscopy, and first-principles calculation results revealed that different from the traditional SACs, the WO2N2moiety (W coordinated with two O atoms and two N atoms) may be the favored structure for W species. This special structure promoted the energy transfer for enhancing singlet oxygen generation. This work presents an efficient way to prepare more high-efficiency SACs by atomic-scale tailoring and structural evolution tracking at the molecular level.

Photocatalytic conversion of CO2into value-added chemicals is considered to be a promising strategy to capture greenhouse gas as well as produce energy. The exploration of efficient and stable photocatalysts is crucial to promote CO2reduction. Herein, we report the synthesis of a heterogeneous catalyst by integration of iron phthalocyanine (FePc) with g-C3N4viaa simple reflux method, in which FePc works as the catalytic center and g-C3N4acts as the photosensitizer. After 12 h of light irradiation, the CO yield by using the FePc/g-C3N4catalyst is found to be 1696.96 μmol g−1and no liquid products are detected. The mechanism for CO2photoreduction over the FePc/g-C3N4hybrid catalyst is proposed. To enhance its practicality and portability, we further load the powder catalyst on polyester fibers (PET). The obtained FePc/g-C3N4@PET exhibits high activity for CO2reduction under both simulated and natural sunlight, with a CO yield of 493.35 μmol g−1and 490.53 μmol g−1, respectively in 12 h. This work may pave the way to develop an approach for fabricating high-efficient 2D artificial photosynthetic systems for CO2reduction.

In diblock copolymers, the constraining effects of different stereochemical structure of high‐Tmblock on crystallization and melting behaviors of other constituent are supposed to be different. In this work, PEG‐b‐PDLLA and PEG‐b‐PLLA were synthesized, and crystallization kinetics, crystalline structure, melting behaviors of PEG blocks and morphology development in these systems were evaluated. Compared to those connected to PLLA, PEG‐b‐PDLLA exhibited lower crystallization rates, implying that connectivity of amorphous chain exerted more pronounced effect on crystallization rate of PEG than that of steric hindrance of PLLA crystallites. While all PEG‐b‐PDLLA samples showed a single endothermic peak during heating process, multiple melting peaks were observed in PEG‐b‐PLLA associated with composition, crystallization temperature and cooling rate of PLLA. A lamellar structure was formed by the crystallization of PEG in all PEG‐b‐PDLLA, however, when PEG‐b‐PLLA crystallized at room temperature directly, unexpected results occurred: lamellar for diblock copolymers with 31.5 and 48.0 wt% PLA or cylindrical structure for the diblock copolymers with 56.1 and 63.8 wt% PLA. Depending on composition, PEG‐b‐PLLA created one or two types of lamellar stacks after sequential crystallization of PLLA and PEG. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 455–465 Crystallization kinetics, crystalline structure, melting behaviors of PEG blocks, and morphology development of PEG‐b‐PDLLA and PEG‐b‐PLLA were investigated. Compared to those connected to PLLA, PEG‐b‐PDLLA exhibited lower crystallization rates. The PEG‐b‐PDLLA showed a single endothermic peak during the heating process, while multiple melting peaks were observed in PEG‐b‐PLLA associated with composition and crystallization conditions. It is proposed that the multiple melting behaviors are possibly due to the distribution of PEG blocks in the spherulitic microstructure of PLLA.

The structure–property evolution of commercial poly(ethylene terephthalate) (PET) fibers obtained from the different drawing and heat-setting stages in industrial processing was systematically investigated. Upon combination of thermal analysis (DSC and DMA) with crystallization and orientation (WAXD and SAXS), the variation of crystallization and microstructures mainly containing lamellar and microfibrillar crystals following the processes were discussed in connection with properties. Results indicate the significant tenacity increase of fiber in the drawing process is mainly attributed to the orientation development of the interlamellar amorphous region, the interfibrillar extension of amorphous molecular chains, and its entanglement with the lamellae. Accordingly, a decline of shrinkage can be seen as a fact of the coiling of amorphous molecular chains, the formation of rigid amorphous fraction, and the increase of crystallinity. Thus, a new four-phase model has been proposed to clarify the structure–property relationships of the commercial PET industrial fibers.

In the research for the safe and efficiently antibacterial cotton fabrics to minimize risk for human health, an organic–inorganic hybrid material of ZnO nanoparticles (NPs) and quaternary ammonium salt (QAS) was employed to modify cotton fabrics by a dipping–padding–drying method. The synergistic effects of ZnO NPs and QAS on the structure and antibacterial properties of cotton fabrics were studied in detail. Results displayed that the QAS and ZnO NPs were immobilized firmly in cotton fabric by the formation of chemical covalent bonds and silica gel structure. ZnO/QAS/cotton had a good inhibitory effect on the growth of E. coliand S. aureus, with superior antibacterial efficiency of >99.99%. ZnO/QAS/cotton preserved good mechanical property, water absorbability, and limpness. We also provided a detailed analysis of antibacterial mechanism for the hybrid materials. The contact mechanism and the Zn2+release were considered as the main mechanisms for the ZnO/QAS/cotton, while the reactive oxygen species (ROS) generation only had a little contribution to the antibacterial activity. In short, the excellent integrated properties endowed the hybrid cotton fabrics as potential application in many fields, like healthcare, food packaging.

The catalytic conversion of biomass platform chemicals using abundant non-noble metal nanocatalysts is a challenging topic. Here, high-density cobalt oxide nanoparticles loaded on biomass-derived porous N-doped carbon (NC) was fabricated by a tandem hydrothermal pyrolysis and mild nitrate decomposition process, which is a green and cheap preparation method. The Co3O4nanoparticles with the average size of 12 nm were uniformly distributed on the porous NC. The nanocomposites also possessed large surface area, high N content, good dispersibility in isopropanol, and furfural absorbability. Due to these characteristics, the novel cobalt nanocatalyst exhibited high catalytic activity for producing furfuryl alcohol, yielding 98.7% of the conversion and 97.1% of the selectivity at 160 °C for 6 h under 1 bar H2. The control experiments implied that both direct hydrogenation and transfer hydrogenation pathways co-existed in the hydrogenation reaction. The excellent catalytic activity of Co3O4@NC was attributed to the cooperative effects of porous NC and Co3O4nanoparticles. This approach provides a new idea to design effective high-density nonnoble metal oxide nanocatalysts for hydrogenation reactions, which can make full use of sustainable natural biomass.

Humans spend at least 70% of their time indoors, but indoor air pollution has received very little attention compared to outdoor pollution. Indoor air pollutants include inhalable particulate matter, volatile organic pollutants, and biological pollutants. In particular, nicotine in second-hand smoke and pathogenic microorganisms in the air are the most overlooked pollutants, which pose serious threats to human health. Here, low-cost inorganic pigments and diatomite have been selected to modify g-C3N4to obtain five novel g-C3N4-based photocatalysts, which are intensely colored and show excellent nicotine degradation performance under both simulated sunlight and white LED illumination. Five g-C3N4-based photocatalytic textiles obtained by supporting the colored photocatalysts on low-melting-point skin–core composite polyester (LMPET) still exhibited outstanding photocatalytic degradation performance and cyclability in removing nicotine. Some of the photocatalytic textiles also displayed highly efficient bacterial inactivation towards E. coliand S. aureusunder white LED illumination. Mechanistic research has revealed that the combination of inorganic pigments and diatomite effectively promotes the separation of photogenerated electrons and holes. Moreover, •O2-, 1O2, and •OH have been identified as the main active species in the colored photocatalyst systems. Notably, the colored photocatalysts may be used as dyes to make wall coverings, sofa covers, and so on, which could conceivably purify indoor air while playing a decorative role.

Graphdiyne (GDY) has realized significant achievements in lithium-ion batteries (LIBs) because of its unique π-conjugated skeleton with sp- and sp2-hybridized carbon atoms. Enriching the accessible surface areas and diffusion pathways of Li ions can realize more storage sites and rapid transport dynamics. Herein, three-dimensional porous hydrogen-substituted GDY (HsGDY) is developed for high-performance Li-ion storage. HsGDY, fabricated via a versatile interface-assisted synthesis strategy, exhibits a large specific surface area (667.9 m2g–1), a hierarchical porous structure, and an expanded interlayer space, which accelerate Li-ion accessibility and lithiation/delithiation. Owing to this high π-conjugated, conductive, and porous framework, HsGDY exhibits a large reversible capacity (930 mA h g–1after 100 cycles at 1 A g–1), superior cycle (720 mA h g–1after 300 cycles at 1 A g–1), and rate (490 mA h g−1at 5 A g–1) performances. Density functional theory calculations of the low diffusion barrier in the lamination and vertical directions further reveal the fast Li-ion transport kinetics of HsGDY. Additionally, a LiCoO2–HsGDY full cell is constructed, which exhibits a good practical charge/discharge capacity of 128 mA h g–1and stable cycling behavior. This study highlights the advanced design of next-generation LIBs to sustainably develop the new energy industry.

For powder catalysts to be recycled easily and to be applied in practical wastewater treatment, it is imperative to search suitable carriers that can be applied to support catalytic particles. Herein, we highlight a facile route to synthesize an easily recycled photocatalyst using polyethylene terephthalate (PET) to disperse graphitic carbon nitride (g-C3N4) via electrospinning and subsequent hydrothermal treatment. The resultant nanofiber is labeled T-g-C3N4/PET. The design concept is to expose the g-C3N4on the PET surface and convert it from inactivation to re-emergence. g-C3N4is embedded into the PET, which avoids the reunion and unrecyclable deficiencies of powder catalysts. T-g-C3N4/PET was characterized by field-emission scanning electronic microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectra, two-dimensional X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis technologies. T-g-C3N4/PET showed a high photocatalytic activity for the degradation of antibiotics such as sulfaquinoxaline and sulfadiazine under solar irradiation, and the activity was almost unaffected in a high background. The as-obtained catalysts could be reused several times with no loss in performance in cycling photodegradation tests. Finally, a possible pathway and mechanism for degrading sulfaquinoxaline with T-g-C3N4/PET was proposed, respectively, in which holes and the superoxide radical were the predominant active species, and resulted in the oxidative degradation of antibiotics. These results demonstrate that the preparation method may provide a novel idea for supporting nanoscale catalysts for reuse.

The chemistry of enzymes presents a key to understanding the catalysis in the world. In the pursuit of controllable catalytic oxidation, researchers make extensive efforts to discover and develop functional materials that exhibit various properties intrinsic to enzymes. Here we describe a bioinspired catalytic system using ordered-mesoporous-carbon (OMC)-bonded cobalt tetraaminophthalocyanine (CoTAPc-OMC) as a catalyst that could mimic the space environment and reactive processes of metalloporphyrin-based heme enzymes and employing linear dodecylbenzenesulfonate as the fifth ligands to control the activation of H2O2toward the peroxidase-like oxidation. The generation of nonselective free hydroxyl radicals was obviously inhibited. In addition, functional modification of OMC has been achieved by a moderate method, which can reduce excessive damage to the structure of OMC. Because of its favorable and tunable pore texture, CoTAPc-OMC provides a suitable interface and environment for the accessibility and oxidation of C.I. Acid Red 1, the model compound, and exhibits significantly enhanced catalytic activity and sufficient stability for H2O2activation. The high-valent cobalt oxo intermediates with high oxidizing ability have been predicted as the acceptable active species, which have been corroborated by the results from the semiempirical quantum-chemical PM6 calculations.

Iron tetranitrophthalocyanine (FePc) was modified and immobilized on carbon fiber (FePc(NO2)3–CF) by covalent bond to obtain a supported heterogeneous catalyst for the removal of dibenzothiophene (DBT) in tridecane. In the supported catalytic system, the catalyst exhibited an excellent catalytic performance without any sacrificial agents, and the conversion of DBT could reach 92 % at 130 °C and 0.2 MPa of initial dioxygen pressure for 3 h. Compared to unsupported FePc, the introduction of carbon fiber dramatically improved the catalytic activity of FePc and facilitated the reuse of catalysts. The amount of FePc(NO2)3–CF, temperature and the initial pressure of molecular oxygen were also studied in detail to optimize the reaction conditions. The removal of DBT significantly increased with the increasing of concentration of DBT in model oil. Finally, a mechanism involving high-valent iron oxo species was proposed for the oxygenation. This study provides new insights into industrial desulfurization systems using carbon fiber as catalyst carrier.